back firing - The 1947 - Present Chevrolet & GMC Truck Message Board Network

67cst · 09-18-2003, 12:24 AM

hey guys, the 71 that i got 2 weeks ago is running good but i notice when im climbing a hill or giving it a fair bit of gas it back fires a bit, not loud at all, more like a pop, it seems like its miss firing almost, what is causing this? should i put some new plugs and wires in? would it be the propane maybe...ive heard when its cold propane can act weird...any suggestions would be great

thanks, Derek

hgs_notes · 09-18-2003, 10:42 AM

I'd check the timing and make sure the vacuum advance is hooked up and working.

HG

tom hand · 09-18-2003, 02:02 PM

Quote:

Originally posted by 67cst
would it be the propane maybe...ive heard when its cold propane can act weird...

I'ts cold up there already? Propane will not tolarate cold at all, so here's some simple things to check. Make sure your radiator is full...if it is low it will starve the vaporizer of water and the propane will start to freeze up. What temp is your motor running at? If it is running pretty cool, [less than 185] step up to a warmer thermostat.

67cst · 09-18-2003, 03:24 PM

thanks for the ideas and stuff to check guys, it isnt too cold up here yet but i can see my breath outside at night or in the late afternoon...

**John Fabris** · 09-18-2003, 03:33 PM

How old are the plug wires?? Anytime you have an engine that runs good in a non load situation (in park or neutral for example) but then starts to studder and pop under a load (in drive, or your case uphill) the first thing you should check is the plug wires....

67cst · 09-18-2003, 03:51 PM

thanks john, ill check them today, im sure they should be replaced along with plugs...ive never owned a propane vehicle before, is there anything weird i should know, like the plugs wouldnt have a different gap or anything would they?

lukecp · 09-18-2003, 05:58 PM

I would just give it a full tuneup and check for vaccuum leaks.

No clue on the propane spark plugs......

How is the MPG and operating cost compared to regular gas?

70cst10_05 · 09-18-2003, 06:33 PM

check dist. cap for cracks, mine did that for about a week, it would barely pull itself up a big hill

67cst · 09-18-2003, 07:26 PM

thanks and thanks for the ideas, i have no idea what mpg i get on the truck....

dinnut · 09-18-2003, 09:48 PM

what? propane trucks? im confused... you use propane?

09-18-2003, 12:24 AM	#1
67cst i love summertime Join Date: Jul 2002 Location: Kelowna BC Posts: 4,303	back firing hey guys, the 71 that i got 2 weeks ago is running good but i notice when im climbing a hill or giving it a fair bit of gas it back fires a bit, not loud at all, more like a pop, it seems like its miss firing almost, what is causing this? should i put some new plugs and wires in? would it be the propane maybe...ive heard when its cold propane can act weird...any suggestions would be great thanks, Derek __________________ 1967 shortbox stepside Chevy, 365 hp 327, th400. GLOVE BOX LIGHTS FORSALE, click link for info http://67-72chevytrucks.com/vboard/s...d.php?t=273724

09-18-2003, 10:42 AM	#2
hgs_notes GEARHEAD Join Date: Aug 2003 Location: MN Posts: 6,122	I'd check the timing and make sure the vacuum advance is hooked up and working. HG __________________ If no one knows what you're doing, they can't tell you you're doing it wrong HG's Dream Car Build - Shelby Cobra Kit Build your own adjustable track bar 71 Long Fleet C/10 72 Jimmy 4x4 (Junkyard Jimmy) HG's Plow Truck '78 K35 Dually Bigass Farm Truck HG's thread of miscellaneous stuff

09-18-2003, 03:24 PM	#4
67cst i love summertime Join Date: Jul 2002 Location: Kelowna BC Posts: 4,303	thanks for the ideas and stuff to check guys, it isnt too cold up here yet but i can see my breath outside at night or in the late afternoon... __________________ 1967 shortbox stepside Chevy, 365 hp 327, th400. GLOVE BOX LIGHTS FORSALE, click link for info http://67-72chevytrucks.com/vboard/s...d.php?t=273724

09-18-2003, 03:33 PM	#5
John Fabris TOTY 2006 Join Date: Dec 1999 Location: Magalia CA USA Posts: 2,270	How old are the plug wires?? Anytime you have an engine that runs good in a non load situation (in park or neutral for example) but then starts to studder and pop under a load (in drive, or your case uphill) the first thing you should check is the plug wires.... __________________ John Fabris 67 C10 SWB

09-18-2003, 03:51 PM	#6
67cst i love summertime Join Date: Jul 2002 Location: Kelowna BC Posts: 4,303	thanks john, ill check them today, im sure they should be replaced along with plugs...ive never owned a propane vehicle before, is there anything weird i should know, like the plugs wouldnt have a different gap or anything would they? __________________ 1967 shortbox stepside Chevy, 365 hp 327, th400. GLOVE BOX LIGHTS FORSALE, click link for info http://67-72chevytrucks.com/vboard/s...d.php?t=273724

09-18-2003, 05:58 PM	#7
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	I would just give it a full tuneup and check for vaccuum leaks. No clue on the propane spark plugs...... How is the MPG and operating cost compared to regular gas? __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

09-18-2003, 06:33 PM	#8
70cst10_05 Registered User Join Date: Dec 2002 Location: Summerfield, Ks Posts: 741	check dist. cap for cracks, mine did that for about a week, it would barely pull itself up a big hill __________________ 1970 Chevy CST/10 1970 Chevy CST/10 1972 Chevy C/10 1972 Chevy Suburban K/10 2019 Silverado 2500 Duramax Kevin

09-18-2003, 07:26 PM	#9
67cst i love summertime Join Date: Jul 2002 Location: Kelowna BC Posts: 4,303	thanks and thanks for the ideas, i have no idea what mpg i get on the truck.... __________________ 1967 shortbox stepside Chevy, 365 hp 327, th400. GLOVE BOX LIGHTS FORSALE, click link for info http://67-72chevytrucks.com/vboard/s...d.php?t=273724

09-18-2003, 09:48 PM	#10
dinnut Registered User Join Date: Apr 2003 Location: missouri city, tx Posts: 4,486	what? propane trucks? im confused... you use propane? __________________ 70 longbed 496/th400/Ford 9"



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